Taboos regulate our sexual conduct, race relations, political institutions, and economic mechanisms - virtually every realm of our life. According to 2002 edition of "Encyclopedia Britannica", taboos are "the prohibition of an action or use of an object based on ritualistic distinctions of them either as being sacred and consecrated or as being dangerous, unclean, and accursed".

Jews are instructed to ritually cleanse themselves after having been in contact with a Torah scroll - or a corpse. This association of sacred with accursed and holy with depraved is key to guilt and sense of danger which accompany violation of a taboo.

In Polynesia, where term originated, says Britannica, "taboos could include prohibitions on fishing or picking fruit at certain seasons; food taboos that restrict diet of pregnant women; prohibitions on talking to or touching chiefs or members of other high social classes; taboos on walking or traveling in certain areas, such as forests; and various taboos that function during important life events such as birth, marriage, and death".

Political correctness in all its manifestations – in academe, media, and in politics - is a particularly pernicious kind of taboo enforcement. It entails an all-pervasive self-censorship coupled with social sanctions. Consider treatment of right to life, incest, suicide, and race.

II. Incest

In contemporary thought, incest is invariably associated with child abuse and its horrific, long-lasting, and often irreversible consequences. But incest is far from being clear-cut or monolithic issue that millennia of taboo imply. Incest with minors is a private - and particularly egregious - case of pedophilia or statutory rape. It should be dealt with forcefully. But incest covers much more besides these criminal acts.

Incest is ethical and legal prohibition to have sex with a related person or to marry him or her - even if people involved are consenting and fully informed adults. Contrary to popular mythology, banning incest has little to do with fear of genetic diseases. Even genetically unrelated parties (a stepfather and a stepdaughter, for example) can commit incest.

Incest is also forbidden between fictive kin or classificatory kin (that belong to same matriline or patriline). In certain societies (such as certain Native American tribes and Chinese) it is sufficient to carry same family name (i.e., to belong to same clan) to render a relationship incestuous. Clearly, in these instances, eugenic considerations have little to do with incest.

Moreover, use of contraceptives means that incest does not need to result in pregnancy and transmission of genetic material. Inbreeding (endogamous) or straightforward incest is norm in many life forms, even among primates (e.g., chimpanzees). It was also quite common until recently in certain human societies - Hindus, for instance, or many Native American tribes, and royal families everywhere. In Ptolemaic dynasty, blood relatives married routinely. Cleopatra’s first husband was her 13 year old brother, Ptolemy XIII.

Nor is taboo universal. In some societies, incest is mandatory or prohibited, according to one's social class (Bali). In others, Royal House started a tradition of incestuous marriages, later emulated by lower classes (Ancient Egypt). The list is long and it serves to demonstrate diversity of attitudes towards this most universal practice.

The more primitive and aggressive society, more strict and elaborate set of incest prohibitions and fiercer penalties for their violation. The reason may be economic. Incest interferes with rigid algorithms of inheritance in conditions of extreme scarcity (for instance, of land and water) and consequently leads to survival-threatening internecine disputes. Most of humanity is still subject to such a predicament.

Freud said that incest provokes horror because it touches upon our forbidden, ambivalent sexual cravings and aggression towards members of our close family. Westermark held that "familiarity breeds repulsion" and that incest taboo - rather than counter inbred instincts - simply reflects emotional reality. Both ignored fact that incest taboo is learned - not inherent.

We can easily imagine a society where incest is extolled, taught, and practiced - and out-breeding is regarded with horror and revulsion. The incestuous marriages among members of royal households of Europe were intended to preserve familial property and expand clan's territory. They were normative, not aberrant. Marrying an outsider was considered abhorrent.

III. Suicide

Social Darwinism, sociobiology, and, nowadays, evolutionary psychology are all derided and disparaged because they try to prove that nature - more specifically, our genes - determine our traits, our accomplishments, our behavior patterns, our social status, and, in many ways, our destiny. Our upbringing and our environment change little. They simply select from ingrained libraries embedded in our brain.

Moreover, discussion of race and race relations is tainted by a history of recurrent ethnocide and genocide and thwarted by dogma of egalitarianism. The (legitimate) question "are all races equal" thus becomes a private case of (no less legitimate) "are all men equal". To ask "can races co-exist peacefully" is thus to embark on slippery slope to slavery and Auschwitz. These historical echoes and overweening imposition of political correctness prevent any meaningful - let alone scientific - discourse.

The irony is that "race" - or at least race as determined by skin color - is a distinctly unscientific concept, concerned more with appearances (i.e., color of one's skin, shape of one's head or hair), common history, and social politics - than with heredity. Most human classificatory traits are not concordant. Different taxonomic criteria conjure up different "races". IQ is a similarly contentious construct, although it is stable and does predict academic achievement effectively.

Thus, racist-sounding claims are as unfounded as claims about racial equality. Still, while former are treated as an abomination - latter are accorded academic respectability and scientific scrutiny.

Consider these two hypotheses:

That IQ (or any other measurable trait) of a given race or ethnic group is hereditarily determined (i.e., that skin color and IQ - or another measurable trait - are concordant) and is strongly correlated with certain types of behavior, life accomplishments, and social status. That IQ (or any other quantifiable trait) of a given race or "ethnic group" is outcome of social and economic circumstances and even if strongly correlated with behavior patterns, academic or other achievements, and social status - which is disputable - is amenable to "social engineering". Both theories are falsifiable and both deserve serious, unbiased, study. That we choose to ignore first and substantiate second demonstrates pernicious and corrupting effect of political correctness.

Claims of type "trait A and trait B are concordant" should be investigated by scientists, regardless of how politically incorrect they are. Not so claims of type "people with trait A are..." or "people with trait A do...". These should be decried as racist tripe.